Anticorrosive



. Patented 1-... 30,1945

UNITED sures PATENT orr cs ANTICOBROSIVE sun a. white, Albany, calm, assign to Shell 7 Development Company, San a corporation of Delaware Francisco, Calif.,

No Drawing. Application February 8,1943.

Serial No. 475,191 I 23 Claims.

boxyl radicals are linked through a nitrogen atom.

Metallic surfaces, particularly those containing iron, require protection against the hazard of corrosion in the presence of water. To illustrate: Moisture readily attacks finished or semifin-ished metal objects unless the metal surface is covered during storage or shipment by a protective coating such as a slushing oil; water in Diesel engine fuels often corrodes closely fittedparts such as are found in Diesel engine unit type injectors; water in turbines corrodes turbine lubricant circulatory systems, particularly the governor mechanisms of steam turbines; and water in hydrocarbon oils such as gasoline rusts steel storage tanks and drums; water in antifreeze compositions causes corrosion in automo- -.bile radiation, etc; Corrosion not only has a deleterious effect upon the metal surfaces, but also frequently loosens .finely divided metal oxmy copendpersed (as in colloidal or true solution) in asuitable vehicle. 1,

I The general formula oLthese acids 'wherein n and m are integers ranging from 1 up toabout 8 and preferably are 1 or 2 The ides'which may act as oxidation catalysts increasing the rate of deterioration of various organic compounds with which they come in contact or may enter between moving parts of machinery where they act as abrasives.

- It is a purpose'of this invention to produce potent corrosion-protective compositions of wide applicability. Another purpose is to produceslushing compositions of improved corrosionprotectiveproperties. A specific purpose is to produce rust-protective hydrocarbon compositions. i. e.. including various Diesel oils, steam turbine oils. greases, etc. Still another purpose is to provide anti-freeze compositions free from a tendency to cause rusting. Further, it is a purpose to produce a non-oily composition which can be used for rust-protection of ferrous metals and in .general for protecting various metals against corrosion.

I have discovered that dicarboxylic acids having at least 16 carbon atoms in which the carboxyl radicals are linked through a trivalent 'nitrogen atom are such potent corrosion inhibitors that they are capable of effectively preventing rusting of ferrous metals, affording protection not only against pure water but against Salt water such as sea water as well. For use in rust-proofing and corrosion prevention in general, ,sm'all amounts of these acids are finely disunoccupied valences: shown are tied to hydrogen or hydrocarbon radicals. The latter mayv be aliphatic, alicyclic, aromatic or mixed and may contain substituents which are preferably not too strongly polar, such as halogen, carbosulfide sulfur; etc, which should preferably be free from highly polar substituents, such as hydroxyl, carboxyl, carbonyl, amino, hydrosulfide,

etc. For maximum stability against deterioration by oxidatio the acid should not contain more than one olefinic double bondper hydrocarbon radical, and preferably none. 25

As indicated above, the acid should have not less than 16 carbon atoms and preferably at least 2.0 and up to about 60 carbon atoms for good anti-corrosive properties. Also the closeness of the nitrogen to the carboxyl radicals has a bearing on this property, in general the closer they are, the greater the protective power. Thus from this angle, homologues in which the nitrogen atom; is in alpha position to at least one carboxyl radical and preferably to both are most desirable. Compounds of this type are the N-amino diacetic'acids, and more speciflcally the N-amino alpha-alpha di-fatty acids.

However, a disadvantage of the N-diacetic acids is their relatively low thermal stability which 1 causes loss of CO2 upon heating to moderately elevated temperatures. For this reason, it .is often desirable to have at least one carboxyl radical separated from the nitrogen atom by 2 or even more carbon atoms. In general, N-amino alpha-beta difatty acids or N-amino beta-beta di-fatty acids are very nearly as potent corrosion inhibitor as the corresponding alpha-alpha compounds. and have a somewhat greater thermal stability.

Accordingly, depending upon the conditions of use, any one of the following three groups of my acids maybe preferred:

Group H Group III eiie coon V In Group I are the N-amino alpha-alpha diiatty acids or corresponding naphthenic or aromatic fatty acids:

' Rr-CHCOOH Binroncoon wherein R1 is a hydrogen or a hydrocarbon radical, and Rs and Rs are hydrocarbon radicals, which in the case of ordinary fatty acids are aliphatic, in the case of naphthenic acids com-' prise cycloaliphatic rings, and in the case of aromatic fatty acids are aromatic or alk-aromatlc.

These dicarboxylic acids may be produced by reacting a primary amine with an alpha halogenated fatty acid, aromatic fatty acid or naphthenic acid as the case may be. Suitable primary amines to be used in this reaction are, for example, ammonia, various alkyl or cycloalkyl amines as methyl, ethyl, propyl, isopropyl, butyl,,

amyl, hezwl, iso-octyl, cyclopentyl, methyl cyclopentyl, cyclohewl, dimethyl cyclohexyl, decyl, tetrallyl, dodecyl, myristyl, cetyl, stearyl, oleyl. etc., amines; or aromatic amines as aniline, toluidine, xylidines, cumidine, naphthylamine, etc. Suitable fatty acids include acetic, propionic, butyric, isobutyric, valeric, caproic, caprylic, decylic, undecylic, lauric, myristic, palmitic, stearic, arachic, behenic, oleic, phenyl acetic,

phenyl propionic, phenyl stearic, tolyl stearic,

naphthyl acetic, naphthyl stearic, acids, etc.

fatty acids. The latter have the formula wherein R1 is hydrogen or a hydrocarbon radical, R: and R3 are hydrocarbon radicals and a: is an integer of 0-4. These acids may be produced by reacting anthranilic acid or homologes thereof with an alpha halogen fatty acid, naphthenic acid, or aromatic fatty acid of the classes described above. I-Iomologues of anthranilic acid are alkyl anthranilic acids, ortho naphthylamine carboxylic acids, alkyl derivatives thereof, etc.

'stants not above about 10-.

Compounds of Group III may be prepared, for

example, by reacting-'HBr with crotonic' acid and Still another type of compound is based on alkylated diphenylamine, said phenyl radical having a .carboxyl radical.

Inasmuch as the acids are relatively little soluble in most vehicles, at-least at ordinary room temperatures, it is usually necessary to produce suitable colloidal dispersions. These may be obtained, for example, by first producing a solution in the vehicle byheating mixtures of the vehicles with the acid to moderately elevated temperatures, and then allowing the solution to cool. This procedure, for instance, is applicable to hydrocarbon oils of suiiiciently high boiling temperatures as kerosene, gas oils, Diesel fuels,

range fuels, lubricating oils, etc.

7 In other cases, a solution may be formed in a solvent, such as a lower alcohol, benzene, etc., which isthen poured into the liquid body of the desired vehicle. In this manner, colloidal dispersions of the acid in oils may be obtained.

The vehicles to which th N-dicarboxylic acids of this invention may be added for the purpose of producing corrosion-protective compositions may be divided into several groups. .In the first place, they may be liquids or plastics, the only requirements as to their physical state being (in addition to their being able to act as carrier for the acids under normal atmospheric conditions) that they be spreadable over metal surfaces. Spreading may be accomplished by immersin flooding, spraying, brushing, trowelling, etc.

After being applied, all or part of the vehicle may be evaporated, or it may be more or less permanent. In other words, both'volatile carriers may be used, or substances which do not materially volatilize under nonnal'atmospheric conditions. As to chemical requirements, the vehicle must be stable under ordinary conditions of storage and use and be inert to the active inhibitors.

Thus the vehicle should preferably be substantially neutral, although it may be weakly acidic or basic, preferably having dissociation con- In vehicles of low dielectric constant, as hydrocarbon oils, which are not conducive to ionization of dissolved electrolytes, relatively small amounts, 1. e., about .1%-5% of various carboxylic acids, such as fatty or naphthenic acids, may be present, and in many instances this may. even be beneficial.

Both polar and non-polar vehicles may be, employed. Among the former are water, alcohols, such as methyl, ethyl, n-propyl, isopropyl, butyl, amyl, hexyl, cyolohexyl, heptyl, methyl cyclohexyl, octyl, decyl, lauryl, myristyl, cetyl, stearyl, benzyl, etc., alcohols; polyhydric alcohols as ethylene glycol,propylene glycol, butylene glycol, glycerol, methyl glycerol, etc.; phenol and various alkyl phenols; ketones as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl, methyl butyl, dipropyl ketones, cyclohexanone and higher ketones; keto alcohols as benzoin; ethers as diethyl ether, diisopropyl ether, diethylene dioxide. beta-beta 'dichlor diethyl ether, diphenyl ascacoc I bon compositions are or special importance. For

oxide, chlorinated diphenyl oxide, diethylene glycol, triethylene glycol, ethylene glycol monomethyl ether. corresponding ethyl, propyl, butyl ethers: neutral esters oi' 'carboxylic and other tanes, benzene, toluene, xylenes, cumene, indene,-

hydrindene, allwl naphthalenes; gasoline distillates, kerosene, gas oil, lubricating oils (which may be soap-thickened to form greases), petrolatu paraflin wax, albino asphalt; carbon tetrachloride, ethylene dichloride, propyl chloride. butyl chloride, chlor benzol, chlorinated kerosene, chlorinated paraflin wax, etc.

The amounts of the dicarboxylic acids which must be incorporated in the above vehicla to produce corrosion-protective compositions vary considerably with the type of vehicle used. As a general rule, the presence of resinous materials,

particularly those of a colloidal nature, calls for relatively larger amountsof inhibitors. Resinous material which interfere with the activity of the inhibitors comprise asphaltenes, petroleum resins, various other natural resins. as rosin, resins formed by polymerization of drying fatty oils, phenol-formaldehyde resins. glyptal type resins formed by esterification of polyhydric alcohols with polycarboxylic acids, etc.

In the absence of such resinous materials, amounts required ofthe N-amino dicarboxylic acids vary from about .001% up to about .1%, although larger amounts may be used. However, where the acids are in colloidal dispersion, rather than in true solution, a concentration in excess of about .1% may result in relatively quick loss of part of the inhibitor by precipitation and settling.

In the presence of resins and other colloids, amounts in excess of .l% and up to 5% may be required. Inasmuch as resins may act as protective colloids, compositions containing these large amounts of colloidally dispersed inhibitors together with resin may be quite resistant to precipitation and settling.

Since resinous and gummy substances in the vehicles do call for greater amounts of inhibitors, it is usually desirable to refine normally liquid vehicles thoroughly and free them from gummy substances, thereby imparting to them maximum inhibitor susceptibility. This is of particular importance, for example, in lubricating oils, speciflcaliy steam turbine oils, which are advantageously highly refined before the inhibitor is introduced. Suitable refining treatments'include, for example, extraction with selective solvent for aromatic hydrocarbons as liquid S02, phenol, furfural, nitrobenzene, aniline, beta-beta-dichlorine diethyl ether, antimony trichloride, etc; treatment with AlCla, sulfuric acid, clay, etc. If the treatment produces a sludge, special care must be taken to'remove it very thoroughly and completely.

Applications of the various corrosion-protective composition vary over a wide range. Hydrocarexample, gasolines stored in drums may cause rusting oi the drums because of the accumulation of water. This is pa ticularly bad in tropical countries where the moisture content of the air is high and wide variations in temperature over a 24-hour cycle cause considerable breathing of the drums. e

Diesel fuels may cause corrosion of injection nozzles.

Lubricating oils and greases made of lubricating oils and soaps normally allow corrosion or even may cause corrosion of various metal parts with which they come in contact, such as :bearings, crank-cases, shafts, etc. This problem arises in many types of engines and is often particularly serious in steamturbines. The presence of the inhibitors of this invention will aflord excellent protection inall of the above instances.

\Rusting of ferrous 'metals exposed to the atmosphere during usage or storage is a serious problem. This is of particular importance where accurately machined parts must be preserved. Slushing oils comprising various types of liquid or plastic hydrocarbons, fats, waxes, lanolin, are employed-to protect the metals against thi attack, and the inhibitors of this invention have great value as an active component in such slushing oils.

Cutting oils, E. P. lubricants due to their content of sulfur and/or chlorine in various active forms, frequently are quite corrosive. The N'- amino di-fatty acids eifectively inhibit this corrosion.

Among the non-hydrocarbon compositions which frequently cause corrosion difficulties, anti-freezes used in automobile radiators and the like may be mentioned. Bhe dicarboiiylic aJcids efliectively eliminate their corrosiveness.

- Anti-freezes usually comprise or consist of watermiscible alcohols, such as methanol, ethanol, isopropanol, glycol, glycerol, etc.

So-called hydraulic oils, damping oils, etc.,

which frequently are :based on non-hydrocarbon liquids, such as various alcohols, esters, etc., have in the past introduced some corrosion difliculties which can effectively be prevented by the acids of this invention. Dispersions of the di-fatty acids in water may be useful in the rust-proofing of metals which after-treatment must not be greasy as, for example, various machine parts inthe textile industries, particularly in the knitting of, line dry goods. If desired, solutions or dispersions in lowboiling alcohols, etc., may be used for the same It is understood that the corrosion-protective compositions ofthis invention may contain other ingredients in addition to the vehicle and the dicarboxylic acids. However, such additiona mgradients must be chemically inert to the acid and the vehicle employed. Thus-strong oxidizing agents as chlorine, peroxides, etc., must be avoided as they tend to destroy the inhibitors. Strong bases, particularly in ionizing vehicles, as in water, alcohols, etc., will neutralize the diacids and thereby render them relatively ineifective. Likewise, strong acids may reduce their effectiveness by forming salts with the nitrogen atom. However, in non-ionizing solvents, i. e., in hydrocarbon compositions, chlorinated hydrocarbons, etc., the presence of relatively small quantities of primary, secondary and tertiary nitrogen bases and/0r carboxylic acids will not normally interfere with the activity of the inhibitor. On the 1 preferably secondary amines, amino phenols; as well as various E. P. compounds containing halogen, S. P, As, etc., anti-wear compounds, detergents, sludge preventing compounds. pour point reducers, thialkenes such as soaps, etc. Likewise, iats, anti-freezes, etc" may contain antioxidants.

Example I The effectiveness of several N-amino dicarboxylic acids in suppressing corrosion was determined by a modified Kuebler test which consists of subjecting-a polished steel strip to the action amount sumeient to retard corrosion of a free dicarboxylic acid having at least 16 carbon atoms.

the carboxyl radicals in said acid being. linked through a trivalent nitrogen atom. a

2. The composition of claim 1 wherein. the number of carbon atoms in said acid is between 20 and 60.

boxylic acid having at least 16 carbon atoms and having the formula of a vigorously stirred emulsion of an oil under test with 10% by volume oi distilled water or oi 0 ).-coon a 2% solution of sodium chloride in distilled I water at 75 C. for 4.8 hours. Results were as C follows: 4 \)..-ooon on Additive Conditions Corrosion Refined lube oil, 150 s. U. at 100 None -f. Distilled water.... 1007 rusted. Do .0017 N-toluidino di-alpha stearic acid 01 ha. 130.. o 6%msted. Do- .0027 N-toluidino til-alpha stearic acid e01 100% rusted. Do. 0 .4 Distilledwater rus 1 50.. .005??? N-toluidino di-aipha stearic acid Cl ogrroslon. O. 0 0. Do- 003% N-octadecylsmino di-al ha stearic acid NaCl Do. Do, Lessthan .01 N-toluidino pha stearic acetic acid Do. Do. Less than .01 o l N-anthranilic a1 ha steaxic acid Do. Do Less1ghan.01% N-ootadecy1 obeta-beta'dipropionic D0.

8'0 Do Less than .0l% N-octadecyl amino alpha proplonic beta- Do.

/ butyric acid.

1 Samples impure, hence amount of active ingredient less than weighed out amount 01 .01%.

Example II The efiectiveness oi toluidino di-alpha stearic acid in enhancing the anti-corrosion propertiesv or a slushing oil was determined by the following test: 7

Two strips of steel /4" x 3" were careful! polished and cleaned to give a bright surface. One strip was coated with a. rust-proofing grease by immersion in a bath consisting of a 50-50 mixture of parafiin was and petrolatum dissolved in a volatile hydrocarbon solvent. The second strip was coated by immersing it in the above bath after 1% of toluidino di-alpha stearic acid had been dissolved therein. The two coated strips were then placed in a horizontal position in a glass dish and 36 drops of a 3% salt solution were deposited on the upper surface of the strips. A loose fitting cover was placed over the dish and it was allowed to stand at room temperature.

The rusting was determined by counting the number of drops that showed signs of rust in any period of time. Results were as iollows:

I claim as my invention:

1. A. corrosion-preventive composition .comprising predominantly a stable substantially neutral vehicle contains: finely dispersed-a small wherein n and m are integers ranging from 1 to about 8, and the unoccupied valences'are tied to hydrogen or hydrocarbon radicals.

7. The composition of claim 6 wherein at least one of said integers m and n is not more than 2.

8. A corrosion-preventive composition comprising a predominantly substantially neutral vehicle containing finely dispersed a small amount sufllcient to retard corrosion of a free dicarboxylic acid having at least 16 carbon atoms and having the formula Rr-CH-COOH M's R;i JHCOOH wherein R1 is a radical selected from the group consisting of hydrogen and hydrocarbons, and R; and R3 are hydrocarbon radicals.

9. A corrosion-preventive composition I comprising predominantly a substantially neutral vehicle containing finely dispersed a. small amount sufiicient to retard corrosion of a free N-amlno alpha-alpha di-fatty acid having at least 16 carbon atoms.

10. A corrosion-preventive composition comprising predominantly a substantially neutral vehicle containing finely dispersed a small amount suificient to retard corrosion of an N-aromatic amine di-fatty acid containing at least 16 carbon atoms. a

11. A corrosion-preventive composition comprising predominantly a substantially neutral vehicle containing finely dispersed a small amount sumcient to retard corrosion of an N-amino alpha-alpha di-stearic acid.

'25 12. A corrosion-preventive composition com- R1 NH-r m-oo on wherein R1 and R2 are hydrocarbon radicals and a: is an integer of 0-4.

14. A corrosion-preventive composition comprising predominantly a substantially neutral vehicle containing finely dispersed a small amount sufilcient to retard corrosion of a free N-anthranilic alpha stearic acid.

15. A corrosion-preventive composition comprising predominantly a substantially neutral oleaginous substance containing a small amount sufiicient to retard corrosion of a free dicarboxylic acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

16. The composition of claim 15 in which said substance is normally liquid.

17. The composition of claim 15 in which said substance is normally plastic.

18. A corrosion-preventive composition comprising predominantly a substantially neutral oleaginous substance free from resins containing finely dispersed .001%-.1% of a free dicar boxylic acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

19. A corrosion-preventive composition comprising predominantly a substantially neutral oleaginous substance containing resins and finely dispersed .1%-5% of a free dicarboxylic acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

20. A corrosion-preventive lubricating oil containing finely dispersed .001%-.1% of a free dicarboxylic acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

21. A corrosion-preventive composition com prising predominantly a carboxylic acid ester containing finely dispersed a small amount of a free dicarboxylic acid having at least 16 carbon atoms, the carboxyl radical'in said acid being linked through a trivalent nitrogen atom.

22. A corrosion-preventive composition comprising predominantly a fat, and finely dispersed therein a small amount of a free dicarboxyiie acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

23. A non-corrosive anti-freeze composition comprising predominantly a water-soluble alcohol and finely dispersed therein a small amount of a free dicarboxylic acid having at least 16 carbon atoms, the carboxyl radical in said acid being linked through a trivalent nitrogen atom.

ELLIS R. WHITE. 

